Unit 3: The digestive and respiratory systems                             1   2   3 

1. Nutrition function

Nutrition is the set of processes, which allow living beings obtain energy and matter to stay alive.

Living means to be able to perform the vital functions (nutrition, interaction and reproduction) and elaborate the own matter in order to replace and repair the damaged parts of the organism.

Nutrition is a complex function in which takes part several organ systems.

Each one of them carries out part of the process and they depend on each other to complete it.

These organ systems are:

    -  Digestive system. It processes and transforms food to obtain

      nutrients which cells are able to assimilate.

    - Respiratory system. It obtains oxygen from air and expels

      carbon dioxide from the vital activity.

    - Circulatory system. Its function is to distribute nutrients

      and oxygen throughout the body and collets the waste substances

      and carbon dioxide from cells.

    - Excretory system. Its function is to expel the waste substances

      out of the body.

1.1. Nutrients are essential substances which living beings need

        to stay alive. Where can they find them?

1.2. What organ systems are involved in bringing oxygen

        to every cell of the body? And glucose?

1.3. Listen and indicate what body system related with the nutrition function 

is described: